The present disclosure provides compositions and methods for using fixed biological samples in partition-based assays. In at least one embodiment, the disclosure provides a composition comprising a fixed biological sample and an un-fixing agent contained in a partition, such as a discrete droplet. In some embodiments, the disclosure provides un-fixing agent compounds capable of catalytically cleaving crosslinks in fixed biological samples, particularly crosslinked nucleic acids, such as RNA.

The present disclosure provides methods for carrying out Romanowsky-type stains, specifically Wright-Giemsa and May-Grünwald stains, quickly and efficiently. The methods greatly reduce the overall amount of time required to complete a Wright-Giemsa stain or a May-Grünwald stain of sufficient quality on a biological sample. The subject methods can be applied to both manual and automated staining procedures.

The method of staining a biological sample includes: a first liquid application step of applying a first liquid onto one of a biological sample or a substrate on which the biological sample is placed, the first liquid containing a water-repellent component and being aqueous; a second liquid application step of applying a second liquid onto one of the biological sample or the substrate, the second liquid containing a thickening component and being aqueous; and a staining solution application step of applying a staining solution for staining the biological sample. The first liquid and the second liquid are applied so as to overlap each other at least partially, to thereby produce a mixed liquid. The first liquid application step and the second liquid application step include applying the first liquid and the second liquid so that the mixed liquid surrounds a region for holding the staining solution.

The present disclosure provides methods for carrying out Romanowsky-type stains, specifically Wright-Giemsa and May-Grnwald stains, quickly and efficiently. The methods greatly reduce the overall amount of time required to complete a Wright-Giemsa stain or a May-Grnwald stain of sufficient quality on a biological sample. The subject methods can be applied to both manual and automated staining procedures.

A formal-in-free fixative composition, suitable for the fixation of cells in particular in liquid samples, the use of said fixative for the treatment of biological samples, a method for the treatment of cell-comprising liquid samples, a kit comprising said fixative and a method for diagnosis of cell-comprising biological material samples.

It has surprisingly been discovered that it is possible to stabilise biomolecules such as RNA, DNA and proteins in biological samples such as cells, tissues, biopsies and blood using deep eutectic solvents (DES). It has also been discovered that DES mixtures can be used to fix and preserve cell morphology in biological samples such as tissue blocks, cancer biopsies and whole blood. This invention describes methods to stabilise and preserve biomolecules, whole cells, tissues, blood and biological samples using DES mixtures.

A single dissolving compound forms plural azeotropes, which can be azeotropically vaporized off at various stages of the treatment process, thus maintaining predictable concentrations of the chemicals present. The treatment process can be performed in the absence of formalin or related compounds which can interfere with the preservation of genetic material. A process for preserving a specimen includes using a dissolving compound that can form a plural number of azeotropes, at least one azeotrope being formed between one or more components of the dissolving compound and specimen-supplied water, and at least one azeotrope being formed between different components of the dissolving compound; successively and azeotropically vaporizing off formed azeotropes; and impregnating the specimen with a support medium.

Matrices and methods of stabilizing and storing biological samples containing nucleic acids are provided. The present application in particular provides systems and methods for stabilizing RNA and especially viral RNA in raw samples, where the stabilization and storage occur before additional processing, isolation, and analytical steps have taken place.

A clearing agent and mounting solution for microscopy is disclosed comprising at least trichloroethanol and/or derivatives thereof, where the refractive index of the solution is greater than or equal to about 1.3810. Also disclosed are methods of preparing specimens for microscopy.

A single dissolving compound forms plural azeotropes, which can be azeotropically vaporized off at various stages of the treatment process, thus maintaining predictable concentrations of the chemicals present. The treatment process can be performed in the absence of formalin or related compounds which can interfere with the preservation of genetic material. A process for preserving a specimen includes using a dissolving compound that can form a plural number of azeotropes, at least one azeotrope being formed between one or more components of the dissolving compound and specimen-supplied water, and at least one azeotrope being formed between different components of the dissolving compound; successively and azeotropically vaporizing off formed azeotropes; and impregnating the specimen with a support medium.